Magnesium alloy



Patented May 30, 1 939 MAGNESIUM ALLOY Arthur Burkhardt, Berlin-Lichterfelde, and Richard Knabe, Berlin-Zehlendort, Germany, as-

signors to Georg Von Giesches Erben, Breslau,

Germany, a corporation oi Germany No Drawing. Application July 2, 1938, Serial No. 217,254. In Germany August 10, 1937 2 Claims. (Cl. 75-168) Our invention relates to magnesium alloys.

It is an object oi our invention to provide a magnesium alloy which possesses high resistance to corrosion and good mechanical properties, and

tinguished by the absence of the heterogenous inclusions acting as local elements in other'magnesium alloys of high strength. At the same time, strength is considerably improved by the formation of the mixed crystals. If the strength of the alloy is increased by hardening and ten pering, segregation does not occur along the magnesium.

. ARTHUR BURKHARD'I'.

RICHARD KRABE.

5 can be used, for instance, in vehicle and aircraft grain boundaries but is distributed uniformly so 5 structures. j that the heat-treated alloyis free from sensi- With the object of our-invention in view, we tivity to internal stress, and from intercrystalmake our alloy as follows: 7 line corrosion.

Percent The preferred percentages of the component in 10 Bismuth gto 6 our novel alloy are as follows. 10 Cadmium to 3 4 to 5 Aluminium 1 to Cadmium, about 2 Zinc ":5 '7' 1 to Aluminium 2 to 4 Remainder Zinc about 3 The remainder or base may be pure, or com- Magnesi Remainder 15 mercially pure, magnesium, or it may consist substantially of magnesium, i. e., a low percent- 1. 2 figf'ggigg zg i g ifigfi fi gi m age of component usually employed g made in magnesium alloys for improving certain nesium 9 for improvmg 'm proper properties, for example, 0.1 to 1% of the followmay be added to the remainder or base. mg metals; manganese for improving cmmslon Magnesium alloys as known at h present time resistance; calcium for improving 'castability; are not quite satisfactory. They either possess smcona metal of the mm group 1 6 iron mgh resistance to cortosion or good mechanical nickel, or cobalt, for increasing the oi f but there Is no magnesium alloy in the alloy at high temperature, and its yield point.

wmc both features are comb to The following table gives examples 01' several Thus a magnesium p which is resistant magnesium alloys according to our invention, the corrosion has poor tensfle strength or the order remainder being substantially magnesium in all of kilogrammes per square millimetre. Concases versely, ii the tensile strength is increased to, say, about 38 kg. per sq. mm., by heat treat- 30 ment or by suitable additions to the alloy, the Alloy 3%;? 323,53?" 333;? $3.3}, 80 alloy is not resistant enough to corrosion. Moreover, such high-tensile alloys are sensitive to in- 5 2 3 ternal stress and-sufler i'rom intergranular corg g g rosion. Addition of manganese improves their cor- 5 3 2 2 35 rosion-resistance but deteriorates their mechang 2 ical properties, particularly their toughness, 6 7. 1 while it does not cure the two weaknesses aiore- 4 3 6 said, since the segregation of the strength-in- 40 creasing components along the grain boundaries It was found that alloy No. 1, in extruded con- 40 I is not suppressed, or the hardening component is dition, has a tensile strength 01' 30 to kg. per. not dissolved h m en usly but appe as a 860- sq. mm., and an elongation or 12V to 5%, and thatond phaseits resistance to corrosion, as tested in the salt- 1 novel y, 011 the th d. is equal to spray apparatus with 3% common salt solution,

45 the best magnes alloys known in corrosion reis practically equal to that of electron, AZ 855, 45

sistance, but far superior in mechanical propwith 3% am mi m, (15 7 1111 0,1 to 0.3% manerties. ganese, remainder magnesium. f

According to our invention, corrosion resist- We claim: ance is not produced by adding known corrosion- 1. A magnesium alloy containing 2 to 6% bis- '50 preventing metals but by suitable selection of the muth, 0.5 to 3% cadmium, 1 to 5% aluminum, components and by determination of the con- 1 to 3.5%zinc, the remainder substantially all centration of saturated mixed crystals, preventmagnesium. ing the formation of a second phaseoi the hard- 2. A magnesium alloy containing 4 to 5% bis- .ening component. muth, about 2% cadmium. 2 to 4% aluminium,

The single-phase alloys thus produced are disabout 3% zinc, the remainder substantially all 56 

